In a multi-axis laser robot in each of which a laser output nozzle is displaceable in three-dimensional directions, a laser beam output from a laser oscillator is directed to an output nozzle through a multistage mirror. Relative distance between the mirrors may be decreased and increased. Such decrease and increase in the relative distance is performed by means of at least three mirrors which are displaceable, respectively in X, Y and Z directions.
When a setting angle of each of the mirrors is not accurately adjusted, a laser beam is not able to be directed along a path to a converging mirror preceding the output nozzle, i.e., parabolic mirror, at a proper position and at a proper angle, so that it is impossible to obtain a laser spot having an appropriate diameter on a surface of a workpiece. In order to eliminate the above inconvenience, an He-Ne (helium-neon) laser provided for adjustment purposes the beam of which is visible, has been conventionally used. A target plate having a scale thereon is perpendicularly disposed just before the mirrors in the beam path so as to determine whether the laser beam is accurately directed at the center of each of the mirrors. When a spot of the laser beam is offset from the center of the scale of the target plate, a mirror preceding the mirror behind the target plate is manually and adjustably pivoted so that the spot of the laser beam may be directed at the center of the scale.
It is noted, however, that such manual adjustment for the mirrors is complicated and time-consuming. It is also possible for the He-Ne laser beam to be disadvantageouly directed to an eye of an operator performing alignment operation when it is inadvertently reflected onto a casing of a watch of the operator.
It is a main object of the invention to provide an automatic alignment-adjustment device and method capable of automatically correcting a setting angle of a mirror to a correct angle.